Anon. Rhai o olion hynafiaethol plwyf Llanddewi Brefi. Transactions of the Cardiganshire Antiquarian Society Vol 1 1911 Welsh Journals Online
Jones, Thomas. The book of the Anchorite of Llanddewi Brefi. Transactions of the Cardiganshire Antiquarian Society Vol 12 1937 Welsh Journals Online
Lewis, W.J. Hanes Darluniadol o Geredigion (An illustrated history of Dyfed) Vol 1. Cardiganshire. Aberystwyth, 1976. Also by same author; An Illustrated History of Cardiganshire. 1970. bilingual text. numerous b/w illus., maps, drawing. Here is a list of the chapter headings and an online index of photographs, and linked from the chapter headings section there is also a list of Tai Unnos [One-Night Houses] built on Mynydd Llanddewibrefi from a diagram in said book
Meyrick, Sir Samuel Rush.(1783-1848) The History and Antiquities of the county of Cardigan. Collected from the few remaining documents which have escaped the ravages of time, as well as from actual observation. Longman: London ,1810. The history and antiquities of the County of Cardigan ... to which are now added a parliamentary history, list of High Sheriffs, some notes on the present county families, &c., &c. repr. Brecon: 1907. This 1907 print has now been reprinted. The section relating to this parish is on pages 249/54; mentioned are Llanio, Gwastad Gwnda, Abermeirig, Voelallt, Glanrocca, and Llwyn.
Rees, D. Ben. Hanes Plwyf Llanddewi Brefi. [History of Llanddewi Brefi Parish].Gomer Press: 1984 [LDS GS 942.95/L1 H2r]
Williams, David Vicar of Llanfair. Y wladfa fach fynyddig. Situated in the parishes of Llanddewibrefi and Llanfairclydogau. Dinbych: 1963. 87pp. Has interesting photographs with names , e.g Brynmeinog Sunday school tea party in 1912, and the Esgairgoch Shearing party in 1920. It lists most of the farms around where David Williams lived, - Esgaircrwys.